A Strategy to Efficiently Extend the Change Rate of Period for Comb-Drive Micromechanical Pitch-Tunable Gratings

In this paper, we present a new design strategy with two major considerations to efficiently extend the change rate of period for comb-drive micromechanical pitch-tunable gratings. The proposed strategy is mainly based on the critical state when “side instability” happens. All the ideas were originated from our previous study to develop a silicon-on-glass (SOG)-based pitch-tunable grating with a large change rate of period, from which we found that once the comb structure was connected with the grating beams, the maximum displacement of movable fingers would be sharply decreased according to the experiments. Detailed discussions and analysis are thus performed to explain the finding. Finally, another grating sample based on the silicon-on-insulator (SOI) technology is developed to prove the new design strategy, and a change rate of period of 10.34% is ultimately achieved. The so-developed pitch-tunable grating will greatly expand the device's application domains.